Product Feature:● New HOP-UP system, ver 6.0 new hammer, and stable bolt lock.● Steel made bolt carrier ＆ fishbone rail (FDE color).● The main receiver is made of aluminum die-casting, which is high precision, high stability and good strength. ● The stock is stronger and not easily broken.● The bolt is adopted by impact-resistant material with a German made connect spring. It is flexible, not easy to break, but easy removal and maintenance; which is also save gas for high airtight characteristic. ● The barrel has very detailed heat sink pattern, which is provided by Montblanc's OEM manufacturer. Steel thin-walled, light weight, and hollow center, the whole process of producing barrel is almost the same level as real gun. ● The inner barrel is a precision one with 6.03mm. ● Nitrided manganese phosphate as surface treatment, which has double cost compared to manganese. This makes the product no rust, and won't scratched.● The gas consumption of M4 magazine is larger than G5's mag. M4 magazine can shooting 1 and half mag a time in auto mode; 2 to 3 mags in semi mode.